30ft hdmi for my projector, will monoprice do the trick?

It should fine. We run one at work with no problem. Lately it seems lik partsexpress.com is cheaper on HDMI cables than momporice.

And, if you haven't already, you should read through this thread, particularly the points over the last two days or so.

http://www.avsforum.com/avs-vb/showthread.php?t=1395991

Standard speed HDMI cables are rated for 1080i/720p. In shorter runs they can support 1080p, but I suggest getting a high speed cable which will be able to handle 1080p no problem

I'm curious, which certified high speed 30' cable have you found that the rest of us haven't? Last we heard the max distance on a high speed cable just a hair over 25'.

I have used 60 foot ( 20 meter) high speed cables. They do 3d 1080p with out any issues. Now if they are certified, that is another question.

If they aren't certified, they don't exist. The only difference between a standard speed cable and a high speed cable is the certification that shows the high speed cable is capable of the maximum HDMI bandwidth, which would be well beyond 1080p/24 3D. Of course, there could be manufacturing and material differences that allow the cable to be certified for high speed versus a standard-speed cable.

What you have is a standard speed HDMI cable that can do 1080p/24 3D. And yes, it is even possible to get a standard speed 50' cable to 1080p/60 with deep color (or even greater lengths) but that doesn't make that a high speed cable and it may not (or may, we don't know) work for 4K. So just because a cable can handle 1080p/24 3D (or even 1080p/60) doesn't make it a true HDMI high speed cable.

Some knock-off manufacturers are claiming to sell high speed cables but all they've done is shown that 1080p/60 works with the cable. That isn't a high speed cable and is in violation of the HDMI adopters agreement. Those are standard speed cables.